Table 1. Characteristics of the Study Population.
| Characteristic | Participants in 1991-1993, No. (%) | P value | Participants in 2002-2004, No. (%) | P value | Participants in 2012-2013, No. (%) | P value | |||
|---|---|---|---|---|---|---|---|---|---|
| Men (n = 2823) | Women (n = 985) | Men (n = 2828) | Women (n = 954) | Men (n = 2910) | Women (n = 986) | ||||
| Sociodemographic factor | |||||||||
| Age, mean (SD) | 49.0 (5.7) | 49.3 (5.8) | .23 | 60.4 (5.7) | 60.4 (5.8) | .89 | 69.4 (5.7) | 69.5 (5.8) | .70 |
| Member of racial or ethnic minority groupa | 153 (5.4) | 123 (12.5) | <.001 | 154 (5.4) | 105 (11.0) | <.001 | 158 (5.4) | 116 (11.8) | <.001 |
| Race and ethnicity | |||||||||
| Black | 40 (1.4) | 55 (5.6) | NA | 37 (1.3) | 41 (4.3) | NA | 40 (1.4) | 46 (4.7) | NA |
| South Asian | 99 (3.5) | 53 (5.4) | NA | 103 (3.6) | 49 (5.1) | NA | 104 (3.6) | 54 (5.5) | NA |
| White | 2670 (94.6) | 862 (87.5) | NA | 2674 (94.6) | 849 (89.0) | NA | 2752 (94.6) | 870 (88.2) | NA |
| Other | 14 (0.5) | 15 (1.5) | NA | 14 (0.5) | 15 (1.6) | NA | 14 (0.5) | 16 (1.6) | NA |
| Occupational positionb | |||||||||
| High | 1426 (50.5) | 206 (20.9) | <.001 | 1592 (56.3) | 255 (26.7) | <.001 | 1657 (56.9) | 270 (27.4) | <.001 |
| Intermediate | 1286 (45.6) | 478 (48.5) | 1141 (40.3) | 470 (49.3) | 1151 (39.6) | 485 (49.2) | |||
| Low | 111 (3.9) | 301 (30.6) | 95 (3.4) | 229 (24.0) | 102 (3.5) | 231 (23.4) | |||
| Not married or cohabitating | 458 (16.2) | 372 (37.8) | <.001 | 459 (16.2) | 420 (44.0) | <.001 | 511 (17.6) | 469 (47.6) | <.001 |
| Behavioral factors | |||||||||
| Smoking status | |||||||||
| Never | 1449 (51.3) | 577 (58.6) | <.001 | 1362 (48.2) | 541 (56.7) | <.001 | 1326 (45.6) | 549 (55.7) | <.001 |
| Past | 1108 (39.2) | 298 (30.3) | 1286 (45.5) | 338 (35.4) | 1499 (51.5) | 398 (40.4) | |||
| Current | 266 (9.4) | 110 (11.2) | 180 (6.4) | 75 (7.9) | 85 (2.9) | 39 (4.0) | |||
| Alcohol intake, units/wk | |||||||||
| None (0) | 358 (12.7) | 254 (25.8) | <.001 | 305 (10.8) | 243 (25.5) | <.001 | 450 (15.5) | 327 (33.2) | <.001 |
| Moderate (1-14) | 1610 (57.0) | 628 (63.8) | 1469 (51.9) | 574 (60.2) | 1643 (56.5) | 564 (57.2) | |||
| High (>14) | 855 (30.3) | 103 (10.5) | 1054 (37.3) | 137 (14.4) | 817 (28.1) | 95 (9.6) | |||
| Fruit and vegetable intake <2 daily | 564 (20.0) | 297 (30.2) | <.001 | 1091 (38.6) | 474 (49.7) | <.001 | 1613 (55.4) | 655 (66.4) | <.001 |
| Health-related factors | |||||||||
| BMI | |||||||||
| Reference range (<25) | 1576 (55.8) | 548 (55.6) | <.001 | 1045 (37.0) | 404 (42.3) | <.001 | 1110 (38.1) | 401 (40.7) | <.001 |
| Overweight (25-29.9) | 1090 (38.6) | 314 (31.9) | 1391 (49.2) | 321 (33.6) | 1347 (46.3) | 330 (33.5) | |||
| Obese (≥30) | 157 (5.6) | 123 (12.5) | 392 (13.9) | 229 (24.0) | 453 (15.6) | 255 (25.9) | |||
| SF-36, mean (SD) | |||||||||
| MCS score | 51.5 (8.1) | 49.7 (9.4) | <.001 | 52.6 (8.4) | 51.0 (10.1) | <.001 | 54.2 (7.6) | 52.3 (9.9) | <.001 |
| PCS score | 53.5 (5.7) | 51.0 (8.1) | <.001 | 50.6 (7.4) | 47.4 (10.0) | <.001 | 49.0 (8.1) | 46.0 (10.6) | <.001 |
| No. of chronic conditions, mean (SD)c | 0.2 (0.5) | 0.2 (0.4) | .03 | 0.6 (0.8) | 0.7 (0.9) | <.001 | 1.2 (1.0) | 1.2 (1.1) | .05 |
| Accelerometer variables, mean (SD), min/d | |||||||||
| Sedentary behavior | NA | NA | NA | NA | NA | NA | 721.5 (98.0) | 708.2 (105.0) | <.001 |
| LIPA | NA | NA | NA | NA | NA | NA | 205.3 (66.6) | 224.2 (74.3) | <.001 |
| MVPA | NA | NA | NA | NA | NA | NA | 58.4 (38.4) | 49.8 (38.2) | <.001 |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); LIPA, light-intensity physical activity; MCS, mental component summary; MVPA, moderate to vigorous physical activity; NA, not applicable; PCS, physical component summary; SF-36, 36-Item Short Form Health Survey.
Race and ethnicity were assessed by questionnaire using the response categories Black, South Asian, White, and other. Racial and ethnic minority groups have been combined in analysis owing to small numbers.
Last occupational position was defined as low (clerical or support positions), intermediate (professional or executive positions), or high (administrative positions), coded as 1, 0.5, and 0, respectively, and entered as an ordinal variable in analyses.
Chronic conditions include hypertension, diabetes, coronary heart disease, stroke, heart failure, arthritis, cancer, depression, dementia, Parkinson disease, and chronic obstructive pulmonary disease.